I think you are missing the argument somewhat.
I am not saying that bf is not beneficial, of course it is. This is not an argument against breastfeeding, extended or otherwise. Interesting that someone presumed I didn't do extended breastfeeding - at what age is extended breastfeeding?
Comparing it to brushing teeth is not a fair analogy. If you don't brush your teeth then your teeth fall out admist lots of pain and you then have to incur the huge cost of false ones. Not to mention gum rot.
But you can choose to ff babies and still be fairly sure that the baby will survive being given a bottle. Whereas in developing countries this is not so because of dirty and contaminated water and bottles. And of course many mothers cannot afford the huge cost of formula milk. So for them it really is a case of you breastfeed or the baby risks death.
At no point in this country do babies risk death if we choose to bottlefeed them.
Yes you may argue about the increased health benefits of breastfeeding and the increased health risks of not doing so. But the risks involved in bottle feeding are still small, you are not condemning your baby to a lifetime of asthma or allergies if you bottle feed, the risk is increased, but not substantially so.
If you do breastfeed of course you are giving the baby a better chance of fighting off these allergies and ailments. But it's not a question of life or death for us.
So when people point to countries such as Ethopia and say they breastfeed the child until the child is 5, they fail to mention that the only reason they do that is because there is a substantial risk the child might catch a fatal disease if they didn't.
I'm not trying to turn this into a bottle versus breast debate, merely pointing out the differences between choice and necessity.